Dynamics Modeling of Bearing with Defect in Modelica and Application in Direct Transfer Learning from Simulation to Test Bench for Bearing Fault Diagnosis

In data-driven bearing fault diagnosis, sufficient fault data are fundamental for algorithm training and validation. However, only very few fault measurements can be provided in most industrial applications, bringing the dynamics model to produce bearing response under defects. This paper built a Modelica model for the whole bearing test rig, including the test bearing, driving motor and hydraulic loading system. First, a five degree-of-freedom (5-DoF) model was proposed for the test bearing to identify the normal bearing dynamics. Next, a fault model was applied to characterize the defect position, defect size, defect shape and multiple defects. The virtual bearing test bench was first developed with OpenModelica and then called in Python with OMPython. For validation of the positive effect of the dynamics model in the direct transfer learning for bearing fault diagnosis, the simulation data from the Modelica model and experimental data from the Case Western Reserve University were fed separately or jointly to train a Convolution Neural Network (CNN). Then the well-trained CNN was transferred directly to achieve the fault diagnosis under the test set consisting of experiment data. Additionally, 157 features were extracted from both time-domain and frequency-domain and fed into CNN as input, and then four different validation cases were designed. The results confirmed the positive effect of simulation data in the CNN transfer learning, especially when the simulation data were added as auxiliary to experimental data, and improved CNN classification accuracy. Furthermore, it indicated that the simulation data from the bearing dynamics model could play a part in the actual experimental measurement when the collected data were insufficient

Thyroid Function Test Abnormalities in Twin Pregnancies

Background: Compared with singletons, a twin pregnancy is associated with a larger thyroid hormone demand and an increased stimulation of gestational thyroid function due to higher concentrations of human chorionic gonadotropin. However, such effects have been sparsely quantified. The aim of this study was to evaluate thyroid function and thyroid function test abnormalities in twin pregnancies during early and late pregnancy compared with singletons. Methods: We included 1208 twin pregnancies and 46,834 singleton pregnancies with thyroid function tests available. Thyroid function test abnormalities were defined using population-based reference ranges. The analyses were adjusted for potential confounders including maternal age and body mass index. Results: Compared with singletons, a twin pregnancy was associated with a lower thyrotropin (TSH) (β = -0.46 [95% confidence interval, CI -0.49 to -0.44], p < 0.001) and a higher free thyroxine (fT4) (β = 0.91 [CI 0.69-1.16], p < 0.001) during early pregnancy. During late pregnancy, a twin pregnancy was associated with a higher TSH (β = 0.35 [CI 0.29-0.42], p < 0.001) while fT4 did not differ (β = -0.11 [CI -0.22 to 0.01], p = 0.065). During early pregnancy, a twin pregnancy was associated with a higher risk of overt hyperthyroidism (odds ratio, OR = 7.49 [CI 6.02-9.33], p < 0.001), subclinical hyperthyroidism (OR = 5.26 [CI 4.17-6.64], p < 0.001), and isolated hypothyroxinemia (OR = 1.89 [CI 1.43-2.49], p < 0.001), but with a lower risk of subclinical hypothyroidism (OR = 0.27 [CI 0.13-0.54], p < 0.001). In late pregnancy, a twin pregnancy was associated with a higher risk of subclinical hypothyroidism (OR = 4.05 [CI 3.21-5.11], p < 0.001), isolated hypothyroxinemia (OR = 1.48 [CI 1.04-2.10], p = 0.028), and subclinical hyperthyroidism (OR = 1.76 [CI 1.27-2.43], p < 0.001). Conclusions: During early pregnancy, a twin pregnancy was associated with a higher thyroid function and a higher risk of (subclinical) hyperthyroidism, as well as a higher risk of isolated hypothyroxinemia. During late pregnancy, a twin pregnancy was associated with a higher TSH concentration and a higher risk of subclinical hypothyroidism, as well as a persistently higher risk of isolated hypothyroxinemia and subclinical hyperthyroidism. The study was approved by Chinese Clinical Trial Registry (registration no. ChiCTR1800014394)

Study protocol for the Sino-Canadian Healthy Life Trajectories Initiative (SCHeLTI): a multicentre, cluster-randomised, parallel-group, superiority trial of a multifaceted community-family-mother-child intervention to prevent childhood overweight and obesity

Introduction Childhood overweight and obesity (OWO) is a primary global health challenge. Childhood OWO prevention is now a public health priority in China. The Sino-Canadian Healthy Life Trajectories Initiative (SCHeLTI), one of four trials being undertaken by the international HeLTI consortium, aims to evaluate the effectiveness of a multifaceted, community-family-mother-child intervention on childhood OWO and non-communicable diseases risk.Methods and analysis This is a multicentre, cluster-randomised, controlled trial conducted in Shanghai, China. The unit of randomisation is the service area of Maternal Child Health Units (N=36). We will recruit 4500 women/partners/families in maternity and district level hospitals. Participants in the intervention group will receive a multifaceted, integrated package of health promotion interventions beginning in preconception or in the first trimester of pregnancy, continuing into infancy and early childhood. The intervention, which is centred on a modified motivational interviewing approach, will target early-life maternal and child risk factors for adiposity. Through the development of a biological specimen bank, we will study potential mechanisms underlying the effects of the intervention. The primary outcome for the trial is childhood OWO (body mass index for age ≥85th percentile) at 5 years of age, based on WHO sex-specific standards. The study has a power of 0.8 (α=0.05) to detect a 30% risk reduction in the proportion of children with OWO at 5 years of age, from 24.4% in the control group to 17% in the intervention group. Recruitment was launched on 30 August 2018 for the pilot study and 10 January 2019 for the formal study.Ethics and dissemination The study has been approved by the Medical Research Ethics Committee of the International Peace Maternity and Child Health Hospital in Shanghai, China, and the Research Ethics Board of the Centre Intégré Universitaire de Santé et Services Sociaux de l’Estrie–CHUS in Sherbrooke, Canada. Data sharing policies are consistent with the governance policy of the HeLTI consortium and government legislation.Trial registration number ChiCTR1800017773.Protocol version November 11, 2020 (Version #5)